Radical S-Adenosylmethionine Enzymes

Radical S-adenosylmethionine (SAM) enzymatic reactions are remarkably diverse, ranging from simple H-atom abstractions to generate product radicals, to H-atom abstractions that initiate a cascade of extraordinary chemical transformations. The members of the radical SAM superfamily exhibit only limited sequence homology. Radical SAM chemistry plays critical roles in numerous biosynthetic pathways including antibiotic production, posttranslational modifications, synthesis of protein cofactors, and catalyzing the synthesis of the nonprotein ligands that impart chemical reactivity to some of the most complex biological metal clusters known. The utilization of a universal protein fold with one of the most ubiquitous metal cofactors in biology, the [4Fe-4S] cluster, together with a simple organic molecule, SAM, is apparently a quite remarkable and adaptable method to carry out a wide variety of difficult transformations.